Anti-tie-down buttons

jhaughery

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J
Join Date
Oct 2005
Location
Lancaster, Pennsylvania
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I am setting up an educational work cell in my University's automation lab. It is a senior thesis project and will be used for educational purposes only. I 'm looking to wire in two anti-tie-down buttons for the start/stop functions of the work cell. I researched the AB 800Z touch buttons, but was wondering if anybody had any suggestions of better brand or model?
 
something a little different: Jokab Safety Balls

safeball.jpg


jstd1mountstation.jpg
 
The 800Z buttons are just fancy buttons....an anti tie down control module is still needed.

If its for an educational lab, save the expense of the 800Z buttons, just get the only the anti tie down controller and wire it to conventional mechanical button such as the 800T or 800H, or if you want to save some more bucks, use the 800E IEC buttons. Look at automationdirect.com for inexpensive buttons - their buttons are more than adequate for an educational lab.


800Z buttons are good for industry where carpal tunnel syndrome and other repetitive motion injury conditions may arise - something thats not likely in your educational lab.
 
jstolaruk said:
something a little different: Jokab Safety Balls
Click to expand...

Kewl. Jokab has some good stuff.

A few years back I was asked to provide an independent review of how a woman got her hands smashed in a machine with two hand control when the two hand control was found to be fully functional. When I got to the customer site I noticed that the machine had un-shrounded PF softstart buttons. The woman wouldn't tell us how the accident happened, but eventually I realized that she leaned into the machine while adjusting some tooling and activated the soft-touch buttons with her breasts. Once we figured it out, she admitted that was what had happened. I had them move the switches and mount them so they were vertical - one facing right, the other left, instead of horizontal in the same plane.

That could not happen with those Jokab safety balls.
 
Alaric said:
Kewl. Jokab has some good stuff.

A few years back I was asked to provide an independent review of how a woman got her hands smashed in a machine with two hand control when the two hand control was found to be fully functional. When I got to the customer site I noticed that the machine had un-shrounded PF softstart buttons. The woman wouldn't tell us how the accident happened, but eventually I realized that she leaned into the machine while adjusting some tooling and activated the soft-touch buttons with her breasts. Once we figured it out, she admitted that was what had happened. I had them move the switches and mount them so they were vertical - one facing right, the other left, instead of horizontal in the same plane.

REPLY Only verifies / corroborates Murphy's law and a very common saying in the safety business
Just when you think you got em all covered some boob finds a way to screw it up.


That could not happen with those Jokab safety balls.
REPLY They do look pretty good on the web page
BUT don't count on it
- I am not going to dare getting anatomical on this one.
I have often wondered about taking 12 year old kids and having them test for fool proof on safety designs OR take the clowns who are "accident prone" and turning them loose - just don't let them have a real machine.

Dan Bentler


Dan Bentler
Click to expand...
 
Alaric said:
..she leaned into the machine while adjusting some tooling and activated the soft-touch buttons with her breasts.
Click to expand...

The buttons should have been spaced further apart (or this was a very 'broad-chested' girl). I use a minimum spacing of 24" (~600mm) between buttons.

🍻

-Eric
 
Eric Nelson said:
The buttons should have been spaced further apart (or this was a very 'broad-chested' girl). I use a minimum spacing of 24" (~600mm) between buttons.
🍻

-Eric
Click to expand...
I thought there was a specific distance for the separation but I can not find it now...I am sure it has something to do with being wider than an average persons body so you have to reach outward to the buttons and can not bend over both at same time.

If its for an educational lab, save the expense of the 800Z buttons, just get the only the anti tie down controller and wire it to conventional mechanical button such as the 800T or 800H, or if you want to save some more bucks, use the 800E IEC buttons. Look at automationdirect.com for inexpensive buttons - their buttons are more than adequate for an educational lab.
Click to expand...
For a lab this may be OK but it could still depend on what is being operated. OSHA regulations in the US for some power presses require the buttons be protected against accidental operation, usually this is read to mean they will have a quard or shield you have to reach into.
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9841

There is also a calculation that determines the distance the buttons and hands have to be from the point of operation.

I offer this for background information, each situations requirements are different.
 
Last edited:
Eric Nelson said:
The buttons should have been spaced further apart (or this was a very 'broad-chested' girl). I use a minimum spacing of 24" (~600mm) between buttons.

🍻

-Eric
Click to expand...

On that particular machine they were about 16-18" apart and because of the workcell arangment they couldn't really be farther apart, hence my recommendation to mount them vertically, one on each side of the machine.


rsdoran said:
For a lab this may be OK but it could still depend on what is being operated.
Click to expand...
Good point Ron. It is the responsibility of the designer to make sure he designs properly for the application.
 
Last edited:
rsdoran said:
I thought there was a specific distance for the separation but I can not find it now...I am sure it has something to do with being wider than an average persons body so you have to reach outward to the buttons and can not bend over both at same time.
Click to expand...
I can't find any specific regulations on this either... :(

Lots of charts and formulas for distance from buttons to hazard, but nothing on minimum spacing of buttons, other than the non-specific word "sufficient"... :rolleyes:

🍻

-Eric
 
Lots of charts and formulas for distance from buttons to hazard, but nothing on minimum spacing of buttons, other than the non-specific word "sufficient"...

OSHA ANSI are full of that "sufficient" and "adequate" ****. Drove me nuts because everyone would argue for days on what was "sufficient" and "adequate"-- In some cases the electrician and I decided when he drilled the holes.

Dan Bentler
 
jhaughery said:
I am setting up an educational work cell in my University's automation lab. It is a senior thesis project and will be used for educational purposes only.
Click to expand...
I have read your post and the replies by others. Here's my question:

If this is for "education", why not have the student research the possibilities him(her)self, learn the details behind OSHA rules and regulations without bias, and then run the various choices by us for additional approvals, feedback, and comments? With our experience, I guarantee all of us will be helpful. (I can suggest "Google-ing" the heck out of the web using "OSHA" "anti-tie down controls", "controls safety", etc. as keywords.)

An early reply said to use cheap "regular" pushbuttons, instead of more expensive anti-tie down pushbuttons designed for safety. I totally disagree. If we are to teach the Controls Engineers of Tomorrow what to do, maybe they should learn the minimum industry standards for safety, not "a cheap way to go".

Some of these engineers go out in the real world and only know what they saw in school. Therefore, a good (or great) example should be set. Just my opinion...
 
FYI My link in the above post goes direct to the OSHA standard for power presses and two hand control.

All the OSHA standards are here:
http://www.osha.gov/pls/oshaweb/owasrch.search_form?p_doc_type=STANDARDS&p_toc_level=0&p_keyvalue=

In many cases two-hand control is used as a safety precaution instead of a legal requirement. The use of standard buttons with a two-hand control relay could be sufficient in a real world application. A risk assessment should be done to determine the proper procedure.

A few years back I rebuilt an L-sealer that used standard buttons and did not require concurrent initiation. I changed the buttons to mushroom head, spaced further apart, and each had an input to the plc. The plc program required concurrent action, each button pressed within .5 seconds. This machine used a sealing arm with hot cut wire that pivoted. I also incorporated a shutdown (arm up/heat off) if the plc did not get a "arm is down signal" within .5 seconds (may have been less in the end). The few modifications I made were not required legally but added to the safety and reliability of the system.
 

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